This invention relates to the field of abrasion-resistant coatings. Specifically there is disclosed a composition of matter including an abrasion-resistant material, the composition being formed into a length of material and wound onto a spool. The abrasion-resistant material can then be deposited onto a surface with the application of heat.
The composition of the present invention is typically applied by welding. The welding apparatus may employ a flame, such as can be produced by an oxyacetylene torch, a TIG process, a so-called atomic hydrogen torch, or other processes using ionization of gases. U.S. Pat. No. 2,219,462 describes examples of compositions adapted to be applied to surfaces by welding. The patent shows such a composition, formed as a length of material. The material is generally formed in straight pieces, several tens of centimeters long. The pieces have a metallic core which is covered with a mixture, the mixture containing the items to be deposited onto the surface. The mixture is in the form of a powder, whose particles are bound together, and bound to the metallic core, by silicate binders.
Other compositions are formed of metallic tubes filled with a metal of a different composition, such as tungsten carbide. These structures have been made in the form of straight, rigid, and relatively short lengths of material. Metallic tubes filled with a different composition have also been formed in long lengths wound on a spool. The latter compositions are used with an automatic electric arc welding process.
The use of discrete lengths of coating materials, in a manual welding process, slows down the process of coating. When surfaces having large areas are being coated, one must use large quantities, i.e. many lengths, of the coating material. But each length of the composition can be used only for a limited time before it is consumed. As the composition is applied to the surface, the length of the piece of material decreases. To avoid the risk of a severe burn, the welder must either discard the butt or weld a new length of material to the butt. The latter procedure is a delicate operation which takes some time. Discarding the butt is also undesirable because it wastes material.
The present invention avoids the disadvantages of the compositions of the prior art, discussed above, and provides a means of increasing the productivity of persons manually applying coatings to surfaces. In particular, the invention provides the abrasion-resistant material in the form of a continuous length, which may be several tens of meters long, and which is sufficiently flexible to be packaged in spools. The composition can easily be wound and unwound, so that no material is wasted.
The present invention thus enjoys substantial advantages over the compositions known in the prior art. Metallic tubes filled with a different material, described above, are very difficult to wind and unwind manually, and they are not very flexible. Special precautions are necessary before handling them.
The composition of the present invention is very flexible, in comparison with the short, rigid lengths of material of the prior art. Despite its flexibility, the present composition can be handled and shipped without special precautions, and is unlikely to form cracks in the material under normal conditions of handling and use. Such cracks are undesirable, because they would cause irregularities in the coating being applied to the surface.
The invention also minimizes the undesirable effects of the metallic core of the composition. The metallic core generally melts at a much higher temperature than does the mixture surrounding the core. With the composition of the present invention, it is possible to reduce the diameter of the core, so that the core does not interfere with the process of applying the abrasion-resistant coating.
It has been difficult to reduce the diameter of the wire core, in compositions of the prior art. While the composition is being formed, it is necessary to guide the wire through an apparatus, and the wire must be guided without causing kinking or jamming problems. The present invention provides a composition which can be formed with a very thin core.
The composition of the present invention can be formed by an extrusion process, the abrasion-resistant material being part of a mixture which is formed around the metallic wire core. The composition can thus be formed in a long length of material, which can be easily wound on a spool and transported. In use, the composition is unwound from the spool, and applied to the surface, usually with a welding torch. It is not necessary to weld together short segments of the composition, or to discard unusable butts of the product.